I've had Mail.app on Lion (and previously Snow Leopard) successfully working with my company's Exchange 2007 for the last couple of years, but today it seems like it's decided not to work. Instead, I get an error message in the UI that it was unable to connect, and in Console.app, the only related message I get seems to be:

And that's all. The connection does work with Outlook, however. A Google search hasn't turned up anything useful. Any thoughts on where I can go with this? Unfortunately our IT team doesn't support Mail.app (only Outlook) and they're even reluctant to support Lion, so they won't be much help, and I'd really rather use Mail.app than that horrible bloatware.

Have you tried deleting the account and adding it back? This has worked for me in the past.
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ephsmithJun 25 '12 at 12:32

Yeah, done that twice. My iCal isn't working either. It all works on my iPhone though. So puzzling.
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JonathanJun 25 '12 at 13:43

I've run into the same bit of confusion before when my iPhone was able to connect and my MB was not. The iPhone connection uses ActiveSync and Mail.app uses Exchange Web Services. Unless the problem on your IT end affected both, you wouldn't have noticed it on your iPhone.
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ephsmithJun 25 '12 at 18:46